Arrangements and methods for avoiding spreading of infectious agents and improving electric safety and suction performance of a medical aspirator

ABSTRACT

Vacuum pump (18) for a medical aspirator (10), the pump (18) comprising a tubular member (20); a piston (22) slidably arranged within the tubular member (20); a piston rod (24) connected to the piston (22); and a coupling mechanism (36) for detachably and functionally connecting the piston rod (24) to a motor (38) for driving the pump (18), wherein the piston rod (24) is configured to reciprocate linearly during operation of the pump (18).

TECHNICAL FIELD

The present disclosure generally relates to the avoidance of spreadinginfectious agents and the improvement of electric safety and suctionperformance, especially in the context of a medical aspirator. Inparticular, various vacuum pumps for a medical aspirator, a motor unitfor a medical aspirator, a disposable arrangement, an arrangement forinactivating infectious agents in an air stream, such as an air streamwithin a medical aspirator, a two-stage canister for a medicalaspirator, an aspiration hose for a canister of a medical aspirator andmedical aspirators including these features are provided. A method forcontrolling the vacuum generated by a vacuum pump is also provided.

BACKGROUND

A medical aspirator, also referred to as a medical suction unit, is acommon device for removing e.g. bodily fluids during medical proceduresor emergency situations. For example, a patient or victim may need to beexposed to vacuum suction to remove bodily fluids and secretions fromthe lungs or other locations. A medical aspirator is a part of thestandard equipment in most ambulances.

WO 9421312 A2 discloses a portable aspirator with a vacuum pump and afluid container arranged within a housing. The pump generates a reducedpressure within the container, enabling fluid to be suctioned from apatient with an aspiration hose and stored within the container. Afilter is connected between the vacuum hose and a connector grommetremovably mounted in an access hole in the housing. The container isdisconnected from the vacuum hose to flush the aspirator between uses.

During use of the aspirator, there is a risk that secretions from thepatient deteriorate the functioning of the filter and infectious agentsmight spread to the pump and the driving electronics. Consequently, thefilter might no longer function to galvanically separate the patientfrom the driving electronics. Since the secretions are oftenelectrically conductive, the patient and the operator risk receiving anelectroshock.

Moreover, infectious agents might stick to other parts of the aspiratorand risk to spread infections. The necessary cleaning and sterilizationprocedures between uses also become complicated and it is thereforedifficult to control the cleanliness of the aspirator.

A further drawback with the portable aspirator in WO 9421312 A2 is thatthe air pumped out to the atmosphere (the exhaust air) might containinfectious agents, in particular when the filter function isdeteriorated. This exposes personnel and patients in vicinity of theaspirator to a health risk. Also the risk of contaminants adhering tosterile tools, surfaces etc. around the aspirator is increased.

SUMMARY

Accordingly, one object of the present disclosure is to providearrangements and methods for avoiding the spreading of infectious agentsand improving electric safety, in particular in connection with amedical aspirator. Moreover, one object of the present disclosure is toprovide reliable galvanic barriers within a medical aspirator. Furtherobjects are to provide solutions improving the performance of andsimplifying the structure of a medical aspirator.

According to one aspect, a vacuum pump for a medical aspirator isprovided, where the pump comprises a tubular member, a piston slidablyarranged within the tubular member, a piston rod connected to thepiston, and a coupling mechanism for detachably and functionallyconnecting the piston rod to a motor for driving the pump, wherein thepiston rod is configured to reciprocate linearly during operation of thepump.

The tubular member may be constituted by a cylinder. Due to the linearlyreciprocating movement of the piston rod, the requirements fortolerances between the tubular member and the piston can be reduced,thus making it simpler and cheaper to manufacture. Also, a pump unit,e.g. a housing for the pump, can be made more compact.

Since the vacuum pump can be attached to and detached from the motor,the vacuum pump may be made disposable, i.e. made with a rather simplestructure and made from a cheap material, e.g. plastics.

Thus, the pump may be a single use pump. The coupling mechanism may be a“quick coupling”. The coupling mechanism may adopt various forms, suchas a connection with threads, latches, wedges etc.

The vacuum pump may comprise two one-way valves, one valve fordelivering air from a piston chamber within the tubular member to theatmosphere, optionally via an exhaust channel, and one valve fordelivering air from a vacuum channel into the piston chamber.

The vacuum pump may be integrally formed with a disposable canister.Alternatively, the vacuum pump may be attachable to a disposablecanister. With this variant, there can be provided a disposable setincluding one disposable pump and one or a plurality of, for examplefive, disposable canisters. Hospitals and similar institutions usingmedical aspirators may thus subscribe to such disposable sets.

The vacuum pump may further comprise a drive mechanism configured totranslate a rotary motion of the motor to the linearly reciprocatingmotion of the piston rod and the coupling mechanism may be provided onthe drive mechanism. For this drive, the motor may comprise a rotatablemotor shaft.

The rotary motion from the motor may be a rotary motion of a separateshaft driven by an output shaft of the motor, e.g. by means of a belttransmission. In this manner, noise can be reduced and the requirementfor tolerances of the motor mounting can be lowered. However, the linearreciprocation of the piston rod may also be accomplished by transferringa linear motion from a linear motor.

When the coupling mechanism is configured to establish a detachablecoupling between the drive mechanism and the motor, both the drivemechanism and the pump can be made disposable. In this case, a couplingmechanism on the piston rod may be omitted.

The drive mechanism may comprise a first arm, a second arm pivotallyconnected to the first arm and a guiding arrangement for linearlyguiding the first arm along with the linearly reciprocating motion ofthe piston rod. The guiding arrangement may be constituted by a linearbearing.

The first arm may be constituted by the piston rod, or may be fixedlyattached to the piston rod. In case the first arm is constituted by thepiston rod, the guiding arrangement may be configured to linearly guidethe piston rod in the linearly reciprocating motion.

The drive mechanism may alternatively be attached with a couplingmechanism connected to an eccentric on the motor shaft. The second armmay thus constitute an eccentric rod. Thus, the drive mechanism mayresemble a classic locomotive drive. The eccentric may alternatively bereferred to as a base plate or a flywheel.

Alternatively, the drive mechanism may comprise a track member with atrack extending substantially perpendicular to the directions ofreciprocation of the piston rod. By guidingly receiving a pin from themotor shaft (offset with respect to a rotational axis of the motorshaft) in the track, the track member reciprocates linearly along withthe piston rod as the motor shaft rotates. The track member may beslidingly supported within a frame with two inwardly facing grooves.

Although the drive mechanism has been described above as being driven bythe motor shaft, it is also possible to arrange a rotatable intermediateshaft driven by the motor shaft via a belt member. The belt member mayreduce (gear down) the rotational speed of the intermediate shaft inview of the motor shaft. Thus, a drive mechanism described as beingdriven by a motor shaft in the present disclosure may also be driven bysuch intermediate shaft. Further alternative configurations to drive thedrive mechanism by the motor shaft are also conceivable.

The vacuum pump may further comprise a membrane fixed to the piston rodfor sealingly closing the pump, e.g. sealingly closing one region of thepump, such as one side of the pump or a partial area on one side of thepump. The membrane may be flexible and may alternatively be referred toas a diaphragm.

The membrane thereby follows the linearly reciprocating movement of thepiston rod. The linearly reciprocating motion is less harmful to themembrane than reciprocating motions of piston rods moving with varyingangles during their reciprocation.

Since the membrane sealingly closes the pump, the membrane constitutes agalvanic barrier. In case a filter is used (for example in a canisterunit), the filter may constitute a first galvanic barrier and themembrane may constitute a second galvanic barrier.

The membrane may constitute a wall of the pump. The membrane may be agore layer or a PTFE (polytetrafluoroethylene) membrane.

According to a further aspect, a vacuum pump for a medical aspirator isprovided, where the pump comprises a tubular member, a piston slidablyarranged within the tubular member, a piston rod connected to thepiston, and a membrane fixed to the piston rod for sealingly closing thepump, wherein the piston rod is configured to reciprocate linearlyduring operation of the pump. This pump may be configured both asdisposable and non-disposable (i.e. permanently attached to a motor unitof the medical aspirator). The membrane may sealingly close one regionof the pump.

According to a further aspect, a motor unit for a medical aspirator isprovided, where the motor unit comprises a motor for driving a vacuumpump, at least two batteries, where each battery is configured to supplydrive current to the motor, a relay associated with each battery,wherein each relay is configured to operate between an allowing statefor receiving a charge from a mains power supply, and a non-allowingstate in which the charge from the mains power supply is not allowed.The batteries may be of any suitable type, for example lead-acidbatteries.

The batteries and the relays may be arranged within a power distributionunit of the motor unit.

The mains power supply may be a power supply from a building (e.g. ahospital) or from a vehicle (e.g. an ambulance). The mains power supplymay be 12 V DC. The relays of the batteries may be galvanicallyseparated from each other.

The motor unit may further comprise a control unit configured to controlthe at least two batteries to alternatingly supply drive current to themotor. More specifically, the control unit may be configured toalternatingly control the relays such that the relay of the battery thatcurrently supplies drive current to the motor adopts the non-allowingstate and the relay of each one or more remaining batteries adopt theallowing state so that the motor is never electrically connected to themains power supply. In this way, the relays constitute a third galvanicbarrier.

Thus, in case two batteries are used, one battery is being charged andthe other battery delivers a drive current during operation of the motorunit. With this control, the motor unit can be safely connected to themains power supply (e.g. in an ambulance) during a suction operation ofthe medical aspirator.

According to a further aspect, a medical aspirator is provided, wherethe medical aspirator comprises a vacuum pump according to the presentdisclosure and/or a motor unit according to the present disclosure.

Each medical aspirator according to the present disclosure may comprisea canister. The canister may be attached to the pump unit or pump suchthat the pump can establish a vacuum within the canister. The medicalaspirator may also comprise an aspiration hose attached to the canister.Thus, by generating a reduced pressure within the canister, fluids andsecretions can be suctioned from a patient with the aspiration hose andcollected within the canister.

The medical aspirator may also comprise a filter for removing infectiousagents, such as bacteria. The filter may be arranged within a channelbetween the canister and the pump. For example, the filter may bearranged in a vacuum channel within a canister unit (e.g. a canisterhousing). The filter may be a HEPA filter. The canister or the canisterunit may also be disposable.

Throughout the present disclosure, the pump unit may be integrallyformed with the canister or the canister unit. Alternatively, theseparts may be detachably connectable to each other.

According to a further aspect, a disposable arrangement is provided,where the disposable arrangement comprises a first disposable partconnectable to a second part, or forming a joint structure together withthe second part, a flexible enclosure configured to provide a protectiveshield around the second part during use of the first disposable parttogether with the second part, and configured to be inverted to providea protective shield around the first disposable part after completion ofthe use, or during pauses of the use.

The disposable arrangement can be used in a wide range of applicationswhere a “dirty” component should be protected. The protective shield mayconstitute a bacterial shield, a chemical shield, a gas shield and/or adirt shield. As one example, the disposable arrangement may beimplemented in a paint brush where the brush constitutes the firstdisposable part and the shaft constitutes the second part.

In case the brush is detachably connectable to the shaft, the flexibleenclosure may be provided on the brush which is then connected to theshaft. The flexible enclosure may then be wrapped around the shaft ofthe paint brush for protecting the shaft, and preferably also thepainter's hand, during painting. By inverting the flexible enclosure tocover the brush, the brush can be prevented from drying and the shaft isclean since it has been protected by the flexible enclosure during thepainting procedure. The flexible enclosure can also be filled withdetergents, solvents, gases, inhibitors or other relevantsubstances/fluids in the inverted state. The brush with the flexibleenclosure wrapped around may be detached from the shaft and discarded orstored. The assembly does in this manner not spread any dirt, in thiscase mainly paint.

The disposable arrangement may also be implemented in a paint brushwhere the brush is permanently attached to the shaft. The brush and theshaft thereby constitute a joint structure. The joint structure may thusbe a disposable joint structure. The flexible enclosure may protect theshaft in the same manner as described above during a painting procedure.When finished, the flexible enclosure may be inverted to protect thebrush and the entire paint brush (i.e. the joint structure) may bediscarded or stored without spreading any dirt, i.e. paint.

One further conceivable application of the disposable arrangement is forspray cans. Within the present disclosure however, the disposablearrangement is mainly described in the context of a medical aspirator.

Thus, according to one variant, a pump unit for a medical aspirator isprovided, where the pump unit comprises a vacuum pump drivable by amotor of a motor unit, a flexible enclosure configured to provide abacterial shield around the motor unit during a suction operation of themedical aspirator, and configured to be inverted to provide a bacterialshield around the pump unit after completion of the suction operation ofthe medical aspirator.

The flexible enclosure may be a plastic bag. The flexible enclosure maycomprise a closable opening which in an open condition allows theflexible enclosure to be inverted from a state enclosing the second partto a state enclosing the first disposable part and which in a closedcondition forms a part of a substantially fluid tight seal around thesecond part and the first disposable part, respectively.

Thus, according to one variant for a pump unit for a medical aspirator,the flexible enclosure comprises a closable opening which in an opencondition allows the flexible enclosure to be inverted from a stateenclosing the motor unit to a state enclosing the pump unit and which ina closed condition forms a part of a substantially fluid tight (or fluidtight and air tight) seal around the motor unit and the pump unit,respectively.

When the flexible enclosure covers the motor unit, air trapped withinthe flexible enclosure may be suctioned, for example through theclosable opening. It is thereby possible to establish a tight fit of theflexible enclosure to the exterior of the motor unit, for example tofacilitate operation of a user interface on the motor unit. The tightfit of the flexible enclosure on the motor unit also indicates that theprotective shield is intact. The closable opening may be constituted bya zip-lock, or by two zip-locks, where one zip-lock is used to close theopening when the flexible enclosure covers the first disposable part andone zip-lock is used to close the opening when the flexible enclosurecovers the second part.

In case the disposable arrangement is used in the context of a medicalaspirator, the first disposable part is constituted by a pump unit witha vacuum pump for a medical aspirator, the second part is constituted bya motor unit with a motor for the medical aspirator, where the vacuumpump is drivable by the motor, and the flexible enclosure is configuredto provide a bacterial shield around the motor unit during a suctionoperation of the medical aspirator, and configured to be inverted toprovide a bacterial shield around the pump unit after completion of thesuction operation of the medical aspirator.

When the flexible enclosure covers the motor unit (the second part), theenclosure may be said to be in a ready mode or an operational mode. Whenthe flexible enclosure covers the pump unit (the first disposable part),the enclosure may be said to be in a disposal mode. Thus, the flexibleenclosure first protects the motor unit (in the ready mode) and thenprotects the operator (in the disposal mode).

The flexible enclosure may additionally be configured to be inverted toprovide a bacterial shield around the pump unit and a canister unit(also including an aspiration hose) after completion of the suctionoperation of the medical aspirator.

Before and during use of the medical aspirator, when the flexibleenclosure encloses the motor unit, a user interface (e.g. buttons and/orcontrol knobs) can be operated through the flexible enclosure, e.g. bypushing on the flexible enclosure. Upon completion of the suctionoperation, an operator may invert the flexible enclosure such that itencloses the pump unit (optionally also the canister unit). Beforeclosing the flexible enclosure, the operator may also throw used glovesinto the flexible enclosure.

The flexible enclosure may be configured to provide a fluid tight sealaround the motor unit and the pump unit in the ready mode and in thedisposal mode, respectively. This fluid tight seal may additionally beair tight.

The vacuum pump may comprise a membrane and the flexible enclosure maybe integrally formed with the membrane. Thereby, the flexible enclosureand the membrane form one continuous part. The membrane may be the samemembrane as described above, e.g. fixed to a disposable piston rod forsealingly closing one region of the pump.

According to a further aspect, a medical aspirator is provided, wherethe medical aspirator comprises a disposable arrangement with a pumpunit and a pump according to the present disclosure, and a motor unitcomprising a motor for driving the vacuum pump of the pump unit. Thepump unit may be detachably connectable to the motor unit.

According to a further aspect, there is provided an arrangement forinactivating infectious agents (e.g. bacteria) in an air stream, such asan air stream within a medical aspirator, where the arrangementcomprises a channel for guiding an air stream therethrough, the channelbeing at least partly constituted by a material permeable to ultravioletlight, an ultraviolet light source arranged adjacent to the channelconfigured to expose the air stream within a treating section of thechannel to ultraviolet (UV) light.

The ultraviolet light source may be configured to provide UV type C(UVC) light with a wavelength of 200 to 280 nm, such as a wavelength of250 to 280 nm, such as 265 nm. The channel may be designed such that theentire air stream is exposed to ultraviolet light during a given time,i.e. designed in dependency of the flow rate within a channel of aparticular application. The channel may be a vacuum or exhaust channelwithin the medical aspirator.

However, this arrangement may also be used in a wide range of otherapplications, including ventilation arrangements in vehicles (cars,buses, trains, airplanes), medical facilities, patient tents, isolationwards, incubators, etc., where the inlet air can be subjected toultraviolet light from the ultraviolet light source. Further possibleapplication for this arrangement include surgical masks (such assurgical antibacterial masks of the gas mask type) for medicalpersonnel, face masks with assisted ventilation (respirators,cardiopulmonary resuscitation (CPR) masks, etc.) where the ultravioletlight source may be provided to expose the connecting hose toultraviolet light, breathing bags, CPR training manikins etc.

The arrangement may further be used to protect persons with suppressedimmune systems, e.g. after cancer treatment, against infections. Theultraviolet light source may be carried by a person, for example in abackpack or with a belt, and the channel may be constituted by a hosebetween the ultraviolet light source and a face mask. Thus, ambient aircan be desinfected and high mobility can be provided for the personcarrying the arrangement.

The arrangement may further be implemented as a universal portabledevice configured to be detachably attached to, e.g. clamped on, hosesof varying widths and of any type, i.e. for any application. As anexample, the arrangement may be implemented as a clamp-on devicecontaining a battery package and the ultraviolet light source that canbe clamped onto a hose. The clamp-on device may be designed with twopieces, each of a generally half-cylinder appearance, containing orconstituting the battery package and the ultraviolet light source,respectively. The two pieces may be hingedly connected to each other,optionally with a biasing mechanism biasing the two pieces on the hose.Alternatively, or in addition, a strap may be provided to secure thepieces to the hose.

Moreover, the ultraviolet light source may be arranged within a deviceto which one or several hoses can be detachably connected. Such devicemay be portable or stationary. The device may have an opening fordrawing in ambient air. Alternatively, the device may be coupled to aninlet hose, i.e. be arranged between two hoses.

The ultraviolet light source may for example be a LED (light-emittingdiode) light source, a laser, a pulsed laser, a pulsed xenon or a pulsedLED. In case the arrangement is used in connection with a medicalaspirator, the ultraviolet light source may be positioned at anysuitable location for exposing the air stream within the treatingsection to ultraviolet light. For example, the ultraviolet light sourcemay be positioned at the exterior (e.g. configured as a box on top of),or close to the exterior of the pump unit or the motor unit. Thus, thearrangement allows retrofitting on existing medical aspirators.

The ultraviolet light source may also be arranged to expose air withinthe canister to ultraviolet light. Since the air is moving through thecanister, the canister may be said to constitute a channel. Fluids andsecretions collected inside the canister may also be exposed to theultraviolet light to be desinfected.

The channel within the treating section may comprise at least twochannel segments configured to direct the air stream in differentdirections. As an example, the treating section may include twosubstantially parallel channel segments and an interconnecting bend. Asfurther examples, the channel within the treating section may bearranged as a spiral, coil or helix and/or may comprise a plurality ofsubstantially parallel channel segments.

According to a further aspect, there is provided a medical aspiratorcomprising an arrangement for inactivating infectious agents in an airstream according to the present disclosure.

According to a further aspect, there is provided a method forcontrolling the vacuum generated by a vacuum pump driven by a motor in amedical aspirator, where the method comprises detecting the generatedvacuum, and controlling the drive current supplied to the motor based onthe detected generated vacuum.

According to one variant, the drive current supplied to the motor iscontrolled to be linearly proportional to the detected generated vacuum.In this case, a relatively high drive current is supplied to the motorwhen the generated vacuum is low and a relatively low drive current issupplied to the motor when the generated vacuum is high. The motor maybe configured to provide a rotational moment (torque) that isproportional to the drive current. The motor may be a BLDC (brushless DCelectric) motor.

Depending on the particular medical procedure, patient condition, orother factors, it is often preferable to control the level of vacuum towhich the patient is exposed and to set a maximum limit of such vacuumlevel. For example, a patient might be harmed if the aspiration hosesticks within the oral cavity. By controlling the drive current suppliedto the motor in this manner, the maximum vacuum in an aspiration hosecan be limited to a specified threshold.

According to a further aspect, a medical aspirator is provided, wherethe medical aspirator comprises a vacuum pump, a motor configured todrive the vacuum pump, means for detecting the generated vacuum, and acontrol unit configured to control the drive current supplied to themotor according to the present disclosure. The vacuum level generated bythe motor may be derived in various manners. When operating a BLDCmotor, the generated vacuum is proportional to the drive current.However, a dedicated vacuum sensor of known type may also be used todetect the generated vacuum. The medical aspirator according to thepresent disclosure may additionally comprise a mechanical vacuumregulator, for example arranged within the pump unit.

According to a further aspect, a two-stage canister for a medicalaspirator is provided, where the canister comprises a first reservoirwith an inlet for an aspiration hose and an outlet for a vacuum channel,a second reservoir, and a partition member movable from a closedposition, where the partition member is configured to maintain a fluidwithin the first reservoir, to a drain position in order to drain thefluid within the first reservoir to the second reservoir.

The drain position may or may not be an open position where a fluidcommunication is established between the second reservoir and theinlet/outlet of the first reservoir. When the partition member is in theclosed position, the second reservoir is functionally isolated from thefirst reservoir in terms of vacuum build-up (the term “partition member”is selected since this member partitions the first reservoir and thesecond reservoir in the closed position). Thus, the effective volume forvacuum buildup in the canister is reduced when the partition member isin the closed position since vacuum only has to be established withinthe first reservoir and not also within the second reservoir.

As a consequence, the time for vacuum build-up can be reduced. This isuseful since the maximum capacity of many canisters is sometimes neverused or only used occasionally. Moreover, if the canister is to becleaned, the volume required to clean is reduced if the second reservoirhas not been used. Also, the first reservoir can be disposed withoutdisposing the second reservoir, which will keep costs down.

After some time of suction operation with the medical aspirator, thefirst reservoir may be full, or nearly full, or it may be desired toempty the first reservoir for other reasons, for example for hygienicreasons. By maneuvering the partition member from the closed position tothe drain position, a fluid communication may open between the firstreservoir and the second reservoir. Thereby, fluids and secretionswithin the first reservoir can be drained to the second reservoir bygravity.

Throughout the present disclosure, the first reservoir and the secondreservoir may alternatively be referred to as a first chamber and asecond chamber, respectively, or as a first stage canister and a secondstage canister, respectively. The second reservoir may have a largervolume than the first reservoir. The first reservoir may have a volumeof 200 ml to 400 ml, such as 300 ml. The second reservoir may have avolume of 600 ml to 800 ml, such as 700 ml.

The two-stage canister may be disposable. Alternatively, or in addition,it may be formed integrally with or may be detachably attachable to apump, such as a disposable pump.

The two-stage canister may be comprised in a canister unit as describedin the present disclosure. A filter may be provided in the vacuumchannel. The canister unit may further comprise the aspiration hoseand/or the vacuum channel. As mentioned above, fluids and secretions canbe suctioned from a patient with the aspiration hose and collectedwithin the canister by generating a reduced pressure within thecanister.

Both the first reservoir and the second reservoir may be configured towithstand a reduced pressure during operation of the two-stage canisterwith the partition member in the drain position. In other words, boththe first reservoir and the second reservoir may be designed towithstand vacuum build-up. With this configuration, the two-stagecanister can also be operated as a one-stage canister when the partitionmember adopts the drain position, i.e. it can be operated with a largecontinuous volume formed by both the first reservoir and the secondreservoir.

The second reservoir may be flexible. Consequently, the space occupiedby the second reservoir may be reduced. That is, the second reservoirmay expand based on the volume of the fluid drained into the secondreservoir.

The partition member may be movable from the drain position to theclosed position. In other words, the partition member may be reversiblymovable between the closed position and the drain position. In thismanner, the two-stage canister can repeatedly run with a reduced volume(i.e. with the partition member in the closed position) with one orseveral emptying procedures (i.e. with the partition member in the drainposition) between the repeated runs.

For all variants where the partition member is movable from the drainposition to the closed position, the partition member may be biasedtowards the closed position. This may for example be realized with asuitable spring arrangement.

However, the partition member may alternatively be irreversibly movablefrom the closed position to the drain position. This may be beneficialin case a simplified design is sought, such as for disposable two-stagecanisters.

The partition member may comprise a closing piston for sealingly closingthe first reservoir to the second reservoir when the partition member isin the closed position. For example, the first reservoir may beconstituted by a tubular member. In the closed position of the partitionmember, the piston may abut against the rim of the tubular member, i.e.the piston may be larger than the interior profile of the tubularmember. Alternatively, the piston may be received within the tubularmember when the partition member is in, or adopts, the closed position.Naturally, the outer profile of the piston thereby corresponds to theinterior profile of the tubular member. These profiles may be circular,square, etc.

The partition member may comprise a piston rod attached to the closingpiston and the piston rod may extend through the exterior of the firstreservoir. With this design, the part of the piston rod extendingthrough the exterior of the first reservoir functions as a handle andmay be actuated by an operator in order to maneuver the partition memberfrom the closed position to the drain position and/or in the reversedirection.

The partition member may comprise a pressing piston for pressing thefluid within the first reservoir to the second reservoir during movementof the partition member from the closed position to the drain position.In this manner, immediate fluid communication between the secondreservoir and the inlet/outlet can be prevented. In addition, viscousfluids and/or secretions are more reliably drained since they are pushedfrom the first reservoir into the second reservoir. Thus, with thisvariant, it is not needed to rely on gravity for draining the firstreservoir to the second reservoir.

According to a further aspect, a medical aspirator comprising atwo-stage canister according to the present disclosure is provided.

Some prior art aspiration hoses for medical aspirators are deliveredwith, or have as an option, an air inlet at the tip (distal section). Anoperator can disrupt the vacuum generated inside the aspiration hose bylifting the thumb off the air inlet and let air from the atmosphereenter the aspiration hose. This may be desired when the aspiration hosesticks to human tissue in the suction region. The function is analogousto the function of the valve commonly provided on shafts for vacuumcleaners. In some other prior art aspiration hoses, the only way torelieve the vacuum inside the aspiration hose when it sticks to humantissue is to detach the aspiration hose from the canister.

According to a further aspect, an aspiration hose for suctioning fluidsfrom a patient into a canister of a medical aspirator is provided, wherethe aspiration hose comprises an upstream section, a downstream section,and a valve mechanism switchable between an open position and a blockingposition, wherein the valve mechanism is configured to allow thesuctioned fluids to pass from the upstream section to the downstreamsection in the open position, and to block the suctioned fluids in theupstream section from entering the downstream section in the blockingposition.

When the valve mechanism is in the blocking position and a pump of themedical aspirator is running, vacuum is generated in the downstreamsection but not in the upstream section. With the method for controllingthe vacuum generated by a vacuum pump driven by a motor in a medicalaspirator as described herein, the pump will stop when a desired vacuumset point is reached. Thereby, the valve mechanism of the aspirationhose can be used as an on/off actuator for a vacuum pump. This is usefulsince medical suction (aspiration) is normally performed in short timeintervals. Additionally, by controlling the vacuum pump with the valvemechanism, the vacuum pump of the medical aspirator can be stoppedwithout any hazzle, batteries can be saved and the noise can be reduced.

The valve mechanism may also be configured to be positioned in one orseveral intermediate positions between the blocking position and theopen position. By positioning the valve mechanism in an intermediateposition, the operator can adjust the airflow.

The canister and/or the medical aspirator may be of any type describedherein. For example, the entire aspiration hose may be made ofdisposable plastics. The upstream section and the downstream section mayalternatively be referred to as a distal section and a proximal section,respectively. A distal section of the aspiration hose is closer to thepatient subjected to medical suction and the proximal section is closerto the canister of the medical aspirator. The upstream section may beconstituted by a section immediately downstream of a suction opening ata distal end of the aspiration hose.

The term “blocking position” of the valve mechanism is selected toindicate a substantial blocking of the suctioned fluids. In case allfluid is blocked, the blocking position may also be referred to as aclosing position. Throughout the present disclosure, the blockingposition and the open position may alternatively be referred to as apassive position and an active position, respectively.

The valve mechanism may have a variety of designs in order to accomplishthe switching between the open position and the blocking position. Asone example, the valve mechanism comprises a valve member with anopening part and a closing part. By aligning the closing part with amain channel inside the aspiration hose, the valve mechanism adopts theblocking position. Similarly, by aligning the opening part with the mainchannel inside the aspiration hose, the valve mechanism adopts the openposition. The valve member of the valve mechanism may be guided inside avalve mechanism housing to move between the blocking position and theopen position.

The aspiration hose may further comprise a biasing member configured tobias the valve mechanism into the blocking position. In this manner, thevalve mechanism constitutes a normally-closed valve. According to onevariant, the biasing member is constituted by a spring that pushes thevalve mechanism from the open position to the blocking position. Withthis variant, the operator may push the valve mechanism from theblocking position into the open position as long as fluids are to besuctioned through the aspiration hose. A locking mechanism may beprovided to lock the valve mechanism in the open position and/or in anyintermediate position.

The aspiration hose may further comprise an air inlet for fluidcommunication between the upstream section and the atmosphere when thevalve mechanism adopts the blocking position. The air inlet mayestablish the fluid communication through a wall of the aspiration hosein the upstream section. Such air inlet may be constituted by anopening. A dedicated closing mechanism may be associated with theopening to close the same. Alternatively, the valve mechanism may bearranged to also close this air inlet. In case no such closing mechanismis provided, the operator may still close the opening with a finger,e.g. the thumb.

The aspiration hose may be configured such that fluid communicationbetween the upstream section and the atmosphere is closed when the valvemechanism adopts the open position. According to one variant, this isaccomplished by arranging an air inlet channel between the upstreamsection and the atmosphere via a valve mechanism housing. In case thevalve mechanism comprises a valve member with an opening part and aclosing part, the opening part may be aligned with the main channelinside the aspiration hose and the closing part may be aligned with theair inlet channel when the valve mechanism adopts the open position.Thereby, the main channel is open and the air inlet channel is closedwhen the valve mechanism adopts the open position.

When this valve mechanism is moved from the open position to theblocking position, the closing part is moved from the air inlet channelto the main channel. Thereby, the main channel inside the aspirationhose is blocked and the air inlet channel is open when the valvemechanism adopts the blocking position. Corresponding intermediatepositions of the opening part and the closing part with respect to themain channel and the air inlet channel are also conceivable, e.g. apositioning of the valve member such that both the main channel and theair inlet channel are approximately half open.

According to a further aspect, a canister comprising an aspiration hoseaccording to the present disclosure is provided.

According to a further aspect, a medical aspirator comprising anaspiration hose according to the present disclosure is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, advantages and aspects of the present disclosure willbecome apparent from the following embodiments taken in conjunction withthe drawings, wherein:

FIG. 1: schematically represents a medical aspirator comprising a motorunit, a pump unit and a canister unit;

FIG. 2a : schematically represents a medical aspirator with a flexibleenclosure covering a motor unit;

FIG. 2b : schematically represents the medical aspirator in FIG. 2a withthe flexible enclosure covering a pump unit;

FIG. 3a : schematically represents a drive mechanism;

FIG. 3b : schematically represents a further drive mechanism;

FIG. 4: schematically represents an arrangement for inactivatinginfectious agents in an air stream;

FIG. 5a : schematically represents a two-stage canister with a partitionmember in a closed position;

FIG. 5b : schematically represents the two-stage canister in FIG. 5awith the partition member in a drain position;

FIG. 6a : schematically represents a further two-stage canister with apartition member in a closed position;

FIG. 6b : schematically represents the two-stage canister in FIG. 6awith the partition member in a drain position;

FIG. 6c : schematically represents the two-stage canister in FIGS. 6aand 6b with the partition member again in the closed position;

FIG. 7a : schematically represents a further two-stage canister with apartition member in a closed position;

FIG. 7b : schematically represents the two-stage canister in FIG. 7awith the partition member in a drain position;

FIG. 7c : schematically represents the two-stage canister in FIGS. 7aand 7b with the partition member again in the closed position;

FIG. 8a : schematically represents a further two-stage canister with apartition member in a closed position;

FIG. 8b : schematically represents the two-stage canister in FIG. 8awith the partition member in a drain position;

FIG. 8c : schematically represents the two-stage canister in FIGS. 8aand 8b with the partition member again in the closed position;

FIG. 9a : schematically represents an aspiration hose with a valvemechanism in a blocking position;

FIG. 9b : schematically represents the aspiration hose in FIG. 9a withthe valve mechanism in an open position;

FIG. 9c : schematically represents the aspiration hose in FIGS. 9a and9b with the valve mechanism in an intermediate position;

FIG. 10a : schematically represents a further aspiration hose with avalve mechanism in a blocking position; and

FIG. 10b : schematically represents the aspiration hose in FIG. 10a withthe valve mechanism in an open position.

DETAILED DESCRIPTION

In the following, various vacuum pumps for a medical aspirator, a motorunit for a medical aspirator, a disposable arrangement in the form of apump unit for a medical aspirator, an arrangement for inactivatinginfectious agents in an air stream, such as an air stream within amedical aspirator, a two-stage canister for a medical aspirator, anaspiration hose for a canister of a medical aspirator and respectivemedical aspirators including these features will be described. The samereference numerals will be used to denote the same or similar structuralfeatures.

FIG. 1 schematically represents a medical aspirator 10 comprising amotor unit 12, a pump unit 14 and a canister unit 16.

The pump unit 14 is basically a housing enclosing a vacuum pump 18. Thevacuum pump 18 comprises a tubular member 20, a piston 22 and a pistonrod 24 connected to the piston 22. In FIG. 1, the piston 22 and thepiston rod 24 are integrally formed. However, the piston 22 and thepiston rod 24 may alternatively be formed separately.

The tubular member 20 is implemented as a cylinder in FIG. 1. The pistonrod 24 is configured to reciprocate linearly during operation of thepump 18. Thus, also the piston 22 is configured to reciprocate linearlywithin the tubular member 20 during operation of the pump 18.

A vacuum channel 26 and an exhaust channel 28 are further provided atone side of a piston chamber 30 within the pump unit 14. As can be seenin FIG. 1, the pump 18 comprises two one-way valves (or check valves)32, 34. One valve 34 is arranged to deliver air from the vacuum channel26 into the piston chamber 30 and prevent air in the opposite direction.The other valve 32 is arranged to deliver air from the piston chamber 30via the exhaust channel 28 to the atmosphere and prevent air in theopposite direction. By reciprocating the piston 22 within the tubularmember 20, air is alternatingly suctioned into the piston chamber 30 andpressed out from the piston chamber 30 to suction air from the vacuumchannel 26.

The vacuum pump 18 and all other components within the pump unit 14 aredisposable. In FIG. 1, all these components are made of plastics.

The vacuum pump 18 further comprises a coupling mechanism 36 fordetachable and functional attachment of the piston rod 24 to a motor 38within the motor unit 12. As can be gathered from FIG. 1, the piston rod24 is not attached immediately to the motor 38, but attached via a drivemechanism 40.

The drive mechanism 40 is configured to translate a rotary motion of themotor 38 (more specifically, a motor shaft) into a linearlyreciprocating motion of the piston rod 24. However, the rotary motionfrom the motor 38 may alternatively be a rotary motion of a separateshaft driven by a motor shaft of the motor 38, e.g. by means of anintermediate belt transmission. The linear reciprocation of the pistonrod 24 may also be accomplished by transferring a linear motion from alinear motor. Since the coupling mechanism 36 in FIG. 1 is attachedbetween the piston rod 24 and the drive mechanism 40, the piston rod 24is functionally connected to the motor 38.

The coupling mechanism 36 may adopt various forms. In FIG. 1, thecoupling mechanism 36 is located between the piston rod 24 and the drivemechanism 40. However, the coupling mechanism 36 may alternatively belocated between the drive mechanism 40 and the motor 38, as is alsoindicated by reference numeral “36” in FIG. 1. In this case, also thedrive mechanism 40 may be made disposable, e.g. made of plastics. Inthis way, the pump 18 may comprise the drive mechanism 40.

The canister unit 16 constitutes a housing containing a canister 42. InFIG. 1, the canister unit 16 is illustrated as detachably attached tothe pump unit 14. However, the canister unit 16 may alternatively bepermanently attached to the pump unit 14 or integrally formed with thepump unit 14. In both cases, the canister 42 may be arranged detachablywithin the canister unit 16.

A vacuum channel 26 and a filter 44 are also provided within thecanister unit 16. The vacuum channel 26 within the canister unit 16 isin fluid communication with the canister 42. Although the filter 44 inFIG. 1 is positioned within the canister unit 16, the filter 44 (or anadditional filter) may be provided on the exhaust channel 28.

The filter 44 in FIG. 1 is a HEPA filter and serves to block infectiousagents that have entered the vacuum channel 26, for example due tosplashing within the canister 42. The filter 44 may be said toconstitute a first galvanic barrier.

The respective vacuum channels 26 of the pump unit 14 and the canisterunit 16 are in fluid communication with each other when the pump unit 14is attached to the canister unit 16. Due to the vacuum generated by thepump 18, air is sucked from the canister 42 and into the vacuum channel26.

The canister unit 16 further comprises an aspiration hose 46. In FIG. 1,the aspiration hose 46 is in an operational state, i.e. separated fromthe canister unit 16. Prior to use (and after use), the aspiration hose46 may be attached to the exterior of the canister unit 16, e.g. bymeans of one or more clips. In the operational state, the aspirationhose 46 may be used to suction secretions from a patient into thecanister 42.

The canister unit 16 is disposable. In FIG. 1, all components of thecanister unit 16 are made of plastics. However, one or more alternativedisposable materials may be used.

After a suction operation of the medical aspirator 10, the couplingmechanism 36 can be disengaged to remove the pump unit 14 and thecanister unit 16 from the motor unit 12. Thus, the pump unit 14 and thecanister unit 16 can be discarded. Consequently, any infectious agentscollected within these parts are safely removed from the remainder ofthe medical aspirator 10.

Since the piston rod 24 reciprocates linearly during operation of thepump 18, also the piston 22 reciprocates linearly within the tubularmember 20. The tubular member 20 does thereby not need any clearancearound the piston 22 to allow for angular variations of the piston rod24 and the piston 22. As a consequence, the requirement for tolerancesis reduced and the tubular member 20 can be made more compact.

Still referring to FIG. 1, it can be seen that the pump 18 comprises aflexible membrane 48. The membrane 48 may alternatively be referred toas a diaphragm. The membrane 48 is fixedly and sealingly attached to thepiston rod 24 to follow the linearly reciprocating motion of the pistonrod 24. The membrane 48 is also fixedly and sealingly attached withrespect to the tubular member 20. Although not illustrated, the membrane48 may be fixedly and sealingly attached directly to the tubular member20. The membrane 48 sealingly closes one region (i.e. a part of theright wall in FIG. 1) of the pump 18. In FIG. 1, the membrane 48 is madeof PTFE plastics and is therefore also disposable.

Since the piston rod 24 reciprocates linearly with respect to thetubular member 20, the connection between the piston rod 24 and themembrane 48 does not move in a lateral direction (perpendicular to thereciprocating direction) of the piston rod 24. In other words, thelateral forces acting on the membrane 48 during operation of the pump 18can be reduced or omitted. This opens up for a simpler design (e.g. thepossibility to use a weaker membrane 48) and a reduced dimensioning ofthe membrane 48. The galvanic isolation in the membrane 48 is of coursedependent on the provision of a piston rod 24 of non-conductivematerial.

Due to the configuration of the membrane 48 and the piston rod 24, therisk for contaminants to pass the membrane 48 is reduced or eliminated.Thus, the function of the membrane 48 as a galvanic barrier is improved.The membrane 48 may be said to constitute a second galvanic barrier.Although the pump 18 in FIG. 1 comprising the membrane 48 is disposable,the concept of using the membrane 48 as a galvanic barrier according tothe present disclosure may also be employed for medical aspirators 10with a permanently attached pump 18.

The motor unit 12 in FIG. 1 comprises, in addition to the drivemechanism 40 and the motor 38, also a power distribution unit 50, acontrol unit 52, a user interface 54 and an ultraviolet light source 56.The power distribution unit 50 may be provided with power from a mainspower supply 58. In FIG. 1, the motor unit 12 is implemented as ahousing.

The motor unit 12 may be disconnected from the mains power supply 58 incase the medical aspirator 10 is to be carried to a remote location,e.g. to an accidental site distanced from an ambulance. Thus, the mainspower supply 58 may be a power supply from a building or a from avehicle.

The power distribution unit 50 comprises two batteries 60. Each battery60 is configured to supply drive current to the motor 38 for driving thesame. In FIG. 1, the batteries 60 are lead-acid batteries.

The power distribution unit 50 further comprises two relays 62associated with the respective battery 60. Each relay 62 is switchablebetween an allowing state and a non-allowing state. In the allowingstate of the relay 62, a charge from the mains power supply 58 isallowed to pass to the respective battery 60. In the non-allowing stateof the relay 62, a charge from the mains power supply 58 is not allowedto pass to the respective battery 60. The relays 62 are galvanicallyseparated from each other, i.e. an electrical connection therebetween isprevented.

The control unit 52 is an electronic control unit configured to controlthe two batteries 60 to alternatingly supply drive current to the motor38. For example, the control unit 52 can send signals to the powerdistribution unit 50 indicating which of the batteries 60 should providedrive current to the motor 38. The control unit 52 may switch the drivecurrent supplying battery 60 after a predetermined time or when thebattery 60 currently driving the motor 38 is discharged or nearlydischarged.

Furthermore, by sending control signals to two relays 62 to controltheir switching states, the control unit 52 is configured to control therelays 62 such that the relay 62 of the battery 60 that currentlysupplies drive current to the motor 38 adopts the non-allowing state andthe relay 62 of the other battery 60 that does not supply drive currentto the motor 38 adopts the allowing state. In this manner, the motor 38is never electrically connected to the mains power supply 58. Thus, thetwo relays 62 form a third galvanic barrier and the safety for thepatient treated by the medical aspirator 10 and for the operator of themedical aspirator 10 is increased.

The battery 60 that is not supplying drive current to the motor 38 andthat has its corresponding relay 62 in the allowing state is beingcharged by the mains power supply 58 (when the medical aspirator 10 isconnected to the mains power supply 58). Thus, with this control of thebatteries 60 by the control unit 52, one battery 60 supplies a drivecurrent to the motor 38 when the other battery 60 is being charged.

In FIG. 1, the motor 38 is a BLDC motor configured to provide arotational moment proportional to the drive current. Since the vacuumgenerated by the vacuum pump 18 is proportional to the drive current ofthe motor 38, the drive current indicates the generated vacuum. Thecontrol unit 52 is configured to control the motor 38 (e.g. via thepower distribution unit 50) based on the detected generated vacuum.Thereby, the vacuum generated by the vacuum pump 18 can be controlled ina simple and reliable manner. Additionally, a conventional mechanicalvacuum regulator within the medical aspirator 10 can be avoided, ormerely used in a complementary manner.

FIGS. 2a and 2b schematically represent a further medical aspirator 10.Mainly differences with respect to FIG. 1 will be described.

The medical aspirator 10 in FIGS. 2a and 2b comprises a pump unit 14, acanister unit 16 and a motor unit 12. Thus, the pump unit 14 comprisesthe vacuum pump 18 driven by the motor 38 of the motor unit 12.

The pump unit 14 further comprises a flexible enclosure 64. As can beseen in FIG. 2a , the flexible enclosure 64 is configured to enclose themotor unit 12 and thereby provide a bacterial shield around the motorunit 12 during a suction operation of the medical aspirator 10. Thus,infectious agents in the atmosphere or on the hands/gloves of anoperator do not stick directly to the motor unit 12. In FIG. 2a , theflexible enclosure 64 is in a ready mode or operational mode.

After completion of the suction operation, the flexible enclosure 64 canbe inverted (i.e. turned “inside-out”) to provide a bacterial shieldaround the pump unit 14, as illustrated in FIG. 2b . In this state,infectious agents previously collected on the outside of the flexibleenclosure 64 in the ready mode are thereby collected and trapped within(e.g. on the inside of) the flexible enclosure 64. The state of theflexible enclosure 64 in FIG. 2b is referred to as a disposal mode.

Thus, by inverting or switching the flexible enclosure 64 in thismanner, the flexible enclosure 64 may first protect the motor unit 12 inthe ready mode (FIG. 2a ) and then protect the operator and otherpersonnel involved in logistics and disposal in the disposal mode (FIG.2b ) from infectious agents and/or secretions. The pump unit 14 and theflexible enclosure 64 thereby constitutes a disposable arrangement wherethe pump unit 14 constitutes a first disposable part and the motor unit12 constitutes a second part to which the first disposable part isconnectable.

The flexible enclosure 64 is described as flexible since it can beinverted, i.e. the flexible enclosure 64 can be bent at some or allregions. The flexible enclosure 64 may or may not stretchable.

As can be seen in FIG. 2b , the flexible enclosure 64 in the disposalmode also provides a bacterial shield around the canister unit 16, inaddition to the pump unit 14. Also the aspiration hose 46 of thecanister unit 16 is captured within the flexible enclosure 64 in thedisposal mode. The operator may also throw used gloves and other wasteinto the flexible enclosure 64 before closing the same around the pumpunit 14 and the canister unit 16.

In the ready mode of the flexible enclosure 64, as illustrated in FIG.2a , when the flexible enclosure 64 encloses the motor unit 12, the userinterface 54 can be operated through the flexible enclosure 64, e.g. bypushing on the flexible enclosure 64.

In case the pump 18 comprises a membrane 48 as described above, themembrane 48 and the flexible enclosure 64 may be integrally formed asone continuous part. The membrane 48 and the flexible enclosure 64 mayeven be formed from the same material.

In FIGS. 2a and 2b , the flexible enclosure 64 is a plastic bag. Theflexible enclosure 64 further comprises a closable opening 66, hereimplemented as a zip-lock. Thereby, when the opening 66 is in a closedcondition, a fluid tight seal is established around the motor unit 12(in the ready mode) or around the pump unit 14 and the canister unit 16(in the disposal mode), as the case may be, by the closed opening 66 andthe flexible enclosure 64. Since the flexible enclosure 64 is a plasticbag, also corresponding air tight enclosures can be established.

In an open condition, the opening 66 is sufficiently large for the motorunit 12 to pass therethrough and for the pump unit 14 and the canisterunit 16 to pass therethrough. Thus, the opening 66 in the open conditionallows the flexible enclosure 64 to be inverted from the ready mode tothe disposal mode.

FIG. 3a schematically represents a drive mechanism 40 for use in amedical aspirator 10 according to the present disclosure. The drivemechanism 40 comprises a first arm 68 and a second arm 70. In FIG. 3a ,the arms 68, 70 are constituted by rigid rods. The first arm 68 ispivotally connected to the second arm 70 about a pivot point 72.

The drive mechanism 40 further comprises a guiding arrangement 74. InFIG. 3a , the guiding arrangement 74 is realized as a linear bearing.The guiding arrangement 74 slidingly supports a linearly reciprocatingmovement of the first arm 68, as indicated with the arrow 76.

In FIG. 3a , the coupling mechanism 36 provides a detachable rigidcoupling between the piston rod 24 and the first arm 68. Thus, thepiston rod 24 and the first arm 68 move together as a unitary rigidstructure.

The motor 38 comprises an eccentric 78 on top of its rotating motorshaft. However, the eccentric 78 may alternatively be separated fromthis motor shaft, for example by means of an intermediate belttransmission. The second arm 70 in FIG. 3a is rotatably connected to theeccentric 78 at a pivot point 80 offset with respect to the rotationalaxis of the motor shaft. The second arm 70 thus constitutes an eccentricrod.

As also indicated in FIG. 3a , the coupling mechanism 36 mayalternatively be attached between the second arm 70 of the drivemechanism 40 and the eccentric 78. In case the coupling mechanism 36 isprovided at this point, the piston rod 24 and the first arm 68 may beintegrally formed (i.e. the coupling mechanism 36 between these partsmay be omitted) and the drive mechanism 40 may be disposable.

FIG. 3b schematically represents a further drive mechanism 40 for use ina medical aspirator 10 according to the present disclosure. Mainlydifferences with respect to FIG. 3a will be described.

This drive mechanism 40 comprises a track member 82 with a track 84extending substantially perpendicular to the reciprocating directions76. A pin 86 is provided on the eccentric 78 and guidingly received inthe track 84. The pin 86 is arranged offset on the eccentric 78 withrespect to a rotational axis of the motor shaft.

The track member 82 is linearly guided within a frame 88. The frame 88comprises two inwardly facing grooves (not shown) in which the outersides of the track member 82 are received.

As can be seen in FIG. 3b , the coupling mechanism 36 may alternativelybe provided in the region of the pin 86. Thus, also the track member 82may be disposable. The track member 82 may be snap-fitted onto the pin86 and engaged within the frame 88 for driving the pump 18 with thedrive mechanism 40. When a suction operation has been completed, thetrack member 82 may be lifted off the pin 86 and a new track member 82(of a new pump 18) may be connected thereto. In this case, the couplingmechanism 36 between the piston rod 24 and the track member 82 may beomitted. Thus, the piston rod 24 may be integrally formed with the trackmember 82.

FIG. 4 schematically represents an arrangement 90 for inactivatinginfectious agents in an air stream. The arrangement 90 can also be usedto inactivate infectious agents in a fluid stream. The air stream may bean air stream within a medical aspirator 10, such as within the vacuumchannel 26 in FIG. 1, either within the pump unit 14 or within thecanister unit 16.

The arrangement 90 in FIG. 4 thus comprises a channel 26 for guiding anair stream therethrough and further comprises an ultraviolet lightsource 56 (in FIG. 1, the ultraviolet light source 56 is provided at theexterior of the motor unit 12). The channel 26 is constituted by amaterial permeable to ultraviolet light, in this case a plasticmaterial. The ultraviolet light source 56 is constituted by a LED lightsource.

The ultraviolet light source 56 is arranged adjacent to the channel 26such that ultraviolet light from the light source 56 is directed to atreating section 92 of the channel 26 (indicated by the dashed lines inFIG. 4). The channel 26 is arranged such that a plurality of channelsegments 94, guiding the air stream in one direction, and a plurality ofchannel segments 96, guiding the air stream in a different direction(the opposite direction in this case), are arranged within the treatingsection 92. The respective channel segments 94, 96 are interconnectedwith a plurality of bends.

The ultraviolet light source 56 may be configured to provide UV type C(UVC) with a wavelength of 200 to 280 nm, such as a wavelength of 250 to280 nm, such as 265 nm. Radiation in the UVC-range of 250 to 280 nmdeactivates bacteria, viruses and other infectious agents by attackingtheir DNA.

Each infectious agent requires a specific dose of UVC to be inactivated.The UV dose (J/m²) is calculated by the UV intensity (mW/cm²) multipliedby the exposure time (s). The predictable dose required for a specificdegree of disinfection is referred to as a “log reduction”, i.e.logarithmic reduction. A 1 log reduction and a 2 log reductioncorrespond to a 90% and a 99% reduction, respectively, of infectiousagents. Each infectious agent is further associated with a specificdose-response curve indicating the required dose to reach various loginactivations.

Since the UV intensity might change (typically decrease) between thelight source 56 and the treating section 92, an ultimate UV intensity atthe light source may be calculated by taking into account parameterssuch as the type or types of infectious agents to be inactivated, dose,log reduction, dose-response relationship, velocity of air (or fluid)stream, light source power and spread angle, how the light spreads etc.The goal is to expose the air stream to a sufficient dose to achieve thewanted log reduction results.

With the design according to FIG. 4, the channel 26 is compactlyarranged within the treating section 92. Thus, the size of the treatingsection 92 may be reduced. Furthermore, the exposure to ultravioletlight may be increased since the air stream travels along an elongateddistance within the treating section 92. The arrangement of the channel26 may however also be compactly arranged within the treating section 92with other designs, including a channel 26 formed as a spiral, coil,helix, or other arbitrary patterns. A wide range of designs may thus beused to expose a large volume of air to UV radiation within a restrictedarea.

FIG. 5a schematically represents a two-stage canister 42 with apartition member 98 in a closed position and FIG. 5b schematicallyrepresents the two-stage canister 42 in FIG. 5a with the partitionmember 98 in a drain position.

The canister 42 may be used with a medical aspirator 10 according to thepresent disclosure. For example, the canister 42 may be comprised in acanister unit 16. The canister unit 16 may be permanently attached ordetatchably attachable to a pump unit 14.

The two-stage canister 42 comprises a first reservoir 100 and a secondreservoir 102, in FIG. 1 implemented as tubular members in the form oftwo cylinders. The first reservoir 100 and the second reservoir 102 mayalternatively be referred to as a first chamber and a second chamber,respectively, or as a first stage canister and a second stage canister,respectively.

The second reservoir 102 has a larger volume than the first reservoir100. The first reservoir 100 has a volume of approximately 300 ml andthe second reservoir 102 has a volume of approximately 700 ml. In thisimplementation, the first reservoir 100 and the second reservoir 102 aremade of disposable plastics.

An aspiration hose 46 and a vacuum channel 26 are attached adjacent tothe top of the first reservoir 100. The aspiration hose 46 is attachedto an inlet 104 of the first reservoir 100 and the vacuum channel 26 isattached to an outlet 106 of the first reservoir 100. The aspirationhose 46 is used to suction patient secretions into the first reservoir100 as described above. The vacuum channel 26 is used to establish avacuum within the first reservoir 100 by means of a pump 18 as describedabove. A filter (not shown) may be provided in the vacuum channel 26 asalso described above.

In FIG. 1, the partition member 98 is implemented as a piston rod 108with a closing piston 110 with an outer diameter larger than the innerdiameter of the first reservoir 100. In the illustrated closed positionof the partition member 98, the closing piston 110 sealingly closes thefirst reservoir 100 to the second reservoir 102 by abutting against thelower rim of the first reservoir 100. Thus, the partition member 98 isconfigured to maintain a suctioned fluid 112 within the first reservoir100.

In the closed position of the partition member 98 in FIG. 5a , thesecond reservoir 102 is functionally isolated from the first reservoir100 so that when running the pump 18, a vacuum is generated within thefirst reservoir 100 but not within the second reservoir 102. In otherwords, the effective volume for vacuum buildup in the two-stage canisteris merely constituted by the volume of the first reservoir 100(approximately 300 ml). Since this effective volume is reduced, the timefor establishing a vacuum sufficient to suction fluids and secretionsfrom a patient with the aspiration hose 46 is reduced.

As illustrated in FIG. 5a , the first reservoir 100 has been filled withthe fluid 112 suctioned from a patient through the aspiration hose 46.In order to drain the fluid 112 within the first reservoir 100 to thesecond reservoir 102, the partition member 98 is moved from theillustrated closed position in FIG. 5a to a drain position asillustrated in FIG. 5b . The movement is illustrated with arrow 114 inFIG. 5b . By lowering the closing piston 110 down from the lower rim ofthe first reservoir 100, a fluid communication between the firstreservoir 100 and the second reservoir 102 is established such that thefluid 112 is drained from the first reservoir 100 to the secondreservoir 102 by means of gravity.

Since the piston rod 108 extends through the exterior of the firstreservoir 100, the part of the piston rod 108 extending outside of thefirst reservoir 100 can be actuated by an operator to maneuver thepartition member 98 from the closed position to the drain position (andin the reverse direction, described later). Thus, the piston rod 108also constitutes a handle.

The fluid communication is also established between the inlet 104 andthe outlet 106 of the first reservoir 100 on the one hand and the secondreservoir 102 on the other hand. Thus, when the partition member 98adopts the drain position as illustrated in FIG. 5b , the effectivevolume of the two-stage canister in terms of vacuum build-up isconstituted by a larger volume, i.e. the volumes of both the firstreservoir 100 and the second reservoir 102 (approximately 1000 ml inthis implementation).

In this implementation, not only the first reservoir 100, but also thesecond reservoir 102 is dimensioned to withstand a reduced pressure,i.e. a vacuum build-up. As an example, both the first reservoir 100 andthe second reservoir 102 may be made of rigid plastics. Consequently, bymaintaining the partition member 98 in the drain position according toFIG. 5b , the two-stage canister 42 can continue to operate as a“one-stage canister”. That is, the subsequent suction operation can becarried out with a large continuous volume formed by both the firstreservoir 100 and the second reservoir 102.

In case it is not needed to run the two-stage canister 42 again with areduced volume, it is possible that the partition member 98 isconfigured to be irreversibly movable from the closed position in FIG.5a to the drain position in FIG. 5b . This could be useful in order toprovide a simple design and/or manufacturing procedure, for example fora disposable two-stage canister 42. As an example, a weak (e.g. plastic)coupling may be provided initially between the first reservoir 100 andthe closing piston 110 to hold these parts together, i.e. to maintainthe partition member 98 in the closed position. By pushing the pistonrod 108 downwardly, the plastic coupling breaks (irreversibly) to allowthe partition member 98 to move into the drain position.

This plastic coupling may form a visible seal (in case the secondreservoir 102 is made of transparent material). Accordingly, if thevisible seal is not broken, it can be assured that no fluid 112 hasentered the second reservoir 102. In this case, only the first reservoir100 may be replaced. The seal may also comprise a material changingcolors when contacted by the fluid 112. Thereby, the visual indicationof a broken seal can be further improved.

The two-stage canister 42 according to FIGS. 5a and 5b may be operatedas follows. With the partition member 98 in the closed position (FIG. 5a), the pump is started to suction fluid 112 into the first reservoir100. Thus, the two-stage canister 42 is used with a lower volume (onlythe first reservoir 100).

When the first reservoir 100 is to be drained, the partition member 98is lowered into the drain position (FIG. 5b ) to drain the fluid 112into the second reservoir 102 by gravity. The pump may continue to runas the second reservoir 102 is being activated. Now, the two-stagecanister 42 is used with a higher volume, i.e. the pump now sucks fluids112 into both the first reservoir 100 and the second reservoir 102.Thus, fluids 112 sucked into the first reservoir 100 continuously draininto the second reservoir 102.

FIG. 6a schematically represents a further two-stage canister 42 with apartition member 98 in a closed position, FIG. 6b schematicallyrepresents the two-stage canister 42 in FIG. 6a with the partitionmember 98 in a drain position and FIG. 6c schematically represents thetwo-stage canister 42 in FIGS. 6a and 6b with the partition member 98again in the closed position. Mainly differences with respect to FIGS.5a and 5b will be described.

In FIGS. 6a, 6b and 6c , the procedure for draining fluid 112 from thefirst reservoir 100 to the second reservoir 102 substantiallycorresponds to the procedure described in connection with FIGS. 5a and5b . However, as illustrated in FIG. 6c , the partition member 98 isalso movable from the drain position in FIG. 6b to the closed positionin FIG. 6c . The movement is illustrated with the arrow 116 in FIG. 6 c.

For all variants where the partition member 98 is movable from the drainposition to the closed position, the partition member 98 may be biasedtowards the closed position. This may for example be realized with asuitable spring arrangement. Thus, the partition member 98 can bepressed by the operator to move from the closed position to the drainposition (direction 114). When the partition member 98 is to move in theopposite direction (direction 116), the partition member 98 can simplybe released and the biasing action on the partition member 98 serves tomove the same from the drain position to the closed position.

Thus, the partition member 98 is in this implementation reversiblymovable between the closed position (FIGS. 6a and 6c ) and the drainposition (FIG. 6b ). Thereby, the two-stage canister 42 can repeatedlyrun with a reduced volume (i.e. with the partition member 98 in theclosed position) with one or several emptying procedures (i.e. with thepartition member 98 in the drain position) between the repeated runs.

In case the canister 42 is only run with a reduced volume, thedimensioning of the second reservoir 102 can be reduced (e.g. made of aweaker plastic than the second reservoir 102 in FIGS. 5a and 5b ) sincethe second reservoir 102 does not have to withstand the reduced pressureduring vacuum build-up. This opens up for a simpler design and thesecond reservoir 102 may only be dimensioned to withstand atmosphericpressure.

However, the second reservoir 102 in FIGS. 6a, 6b and 6c mayalternatively be made of the same rigid material as the second reservoir102 in FIGS. 5a and 5b , i.e. dimensioned to withstand vacuum build-up.In this way, the two-stage canister 42 may be repeatedly run with twodifferent effective volumes.

The two-stage canister 42 according to FIGS. 6a, 6b and 6c may beoperated as follows. With the partition member 98 in the closed position(FIG. 6a ), the pump is started to suction fluid 112 into the firstreservoir 100. Thus, the two-stage canister 42 is used with a lowervolume (only the first reservoir 100).

When the first reservoir 100 is to be drained, the pump is stopped andthe partition member 98 is lowered into the drain position (FIG. 6b ) todrain the fluid 112 into the second reservoir 102 by gravity. Afterdraining the fluid 112, the partition member 98 is moved back into theclosed position (FIG. 6c ), for example by means of the springarrangement. When the partition member 98 has adopted the closedposition, the pump is started anew and a suction cycle with a lowervolume (only the first reservoir 100) is started.

Alternatively, after the fluid 112 has been drained into the secondreservoir 102, the partition member 98 is maintained in the drainposition (FIG. 6b ) and the pump is started anew and a suction cyclewith a higher volume (with both the first reservoir 100 and the secondreservoir 102) is started. In this case, the spring arrangement may beomitted or a locking mechanism for locking the partition member 98 inthe drain position may be provided.

FIG. 7a schematically represents a further two-stage canister 42 with apartition member 98 in a closed position, FIG. 7b schematicallyrepresents the two-stage canister 42 in FIG. 7a with the partitionmember 98 in a drain position and FIG. 7c schematically represents thetwo-stage canister 42 in FIGS. 7a and 7b with the partition member 98again in the closed position. Mainly differences with respect to FIGS.5a, 5b, 6a, 6b and 6c will be described.

In the implementation of FIGS. 7a, 7b and 7c , the second reservoir 102is made of a flexible material, such as a soft plastic bag or bellow.The material of the second reservoir 102 may additionally bestretchable.

In the closed position of the partition member 98 as illustrated in FIG.7a , the second reservoir 102 is empty. Due to the flexibility (andoptionally also the stretchability) of the material of the secondreservoir 102, the space occupied by the second reservoir 102 can bereduced.

Since the second reservoir 102 is flexible, it is not suitable forwithstanding the reduced pressure during vacuum generation. Thus, withthe two-stage canister 42 in FIGS. 7a, 7b and 7c , the partition member98 is held in the closed position during vacuum generation.

After draining the fluid 112 from the first reservoir 100 to the secondreservoir 102 by lowering the partition member 98 (in the direction114), the partition member 98 is raised (in the direction 116) to againadopt the closed position. During vacuum generation inside the firstreservoir 100 for the second time, the fluid 112 from the first cycle iskept inside the second reservoir 102 which thereby occupies an increasedvolume.

The two-stage canister 42 according to FIGS. 7a, 7b and 7c may beoperated as follows. With the partition member 98 in the closed position(FIG. 7a ), the pump is started to suction fluid 112 into the firstreservoir 100. Thus, the two-stage canister 42 is used with a reducedvolume (only the first reservoir 100).

When the first reservoir 100 is to be drained, the pump is stopped andthe partition member 98 is lowered into the drain position (FIG. 7b ) todrain the fluid 112 into the second reservoir 102 by gravity. The secondreservoir 102 expands as the fluid 112 enters the same due to the weightof the fluid 112. In addition, when lowering the partition member 98,the closing piston 110 may help expanding the flexible second reservoir102.

When a new suction cycle is to be started, the partition member 98 ismoved from the drain position (FIG. 7b ) to the closed position (FIG. 7c). Once the partition member 98 has adopted the closed position tosealingly close the first reservoir 100 to the second reservoir 102, thepump is started again to initiate the next suction cycle.

FIG. 8a schematically represents a further two-stage canister 42 with apartition member 98 in a closed position, FIG. 8b schematicallyrepresents the two-stage canister 42 in FIG. 8a with the partitionmember 98 in a drain position and FIG. 8c schematically represents thetwo-stage canister 42 in FIGS. 8a and 8b with the partition member 98again in the closed position. Mainly differences with respect to FIGS.5a, 5b, 6a, 6b, 6c, 7a, 7b and 7c will be described.

The partition member 98 in FIGS. 8a, 8b and 8c further comprises apressing piston 118. The pressing piston 118 is provided on the pistonrod 108 and is arranged to sealingly slide along the interior surface ofthe first reservoir 100. As can be seen in FIG. 8a , when the partitionmember 98 adopts the closed position, the pressing piston 118 isarranged in the upper region of the first reservoir 100 above the inlet104 and the outlet 106. Thereby, the space formed between the pressingpiston 118 and the closing piston 110 inside the first reservoir 100 issubjected to vacuum build-up.

By lowering the partition member 98 in the direction 114 to the drainposition as illustrated in FIG. 8b , fluids and secretions 112 insidethe first reservoir 100 are pushed down to the second reservoir 102 bythe pressing piston 118. Thereby, in case the fluids and secretions 112do not fall down to the second reservoir 102 by means of gravity, thepressing piston 118 pushes these into the second reservoir 102. In thismanner, viscous fluids and/or secretions 112 are more reliably drainedinto the second reservoir 102. As can be gathered from FIGS. 8a, 8b and8c , neither in the closed position (FIGS. 8a, 8c ), nor in the drainposition (FIG. 8b ), nor in any intermediate position of the partitionmember 98 is a fluid communication established between the inlet104/outlet 106 and the second reservoir 102.

The two-stage canister 42 according to FIGS. 8a, 8b and 8c may beoperated as follows. With the partition member 98 in the closed position(FIG. 8a ), the pump is started to suction fluid 112 into the firstreservoir 100. That is, into the space between the pressing piston 118and the closing piston 110 inside the first reservoir 100. Thus, thetwo-stage canister 42 is used with a reduced volume (only the spacebetween the pressing piston 118 and the closing piston 110 within firstreservoir 100).

When the first reservoir 100 is to be drained, the pump is stopped andthe partition member 98 is lowered into the drain position (FIG. 7b ) todrain the fluid 112 into the second reservoir 102 by gravity andsimultaneously press fluids/secretions 112 into the second reservoir 102with the pressing piston 118. The second reservoir 102 expands as thefluid 112 enters the same due to the weight of the fluid 112. Inaddition, when lowering the partition member 98, the closing piston 110may help expanding the flexible second reservoir 102.

When a new suction cycle is to be started, the partition member 98 ismoved from the drain position (FIG. 8b ) to the closed position (FIG. 8c). Once the partition member 98 has adopted the closed position tosealingly close the first reservoir 100 to the second reservoir 102 andonce the pressing piston 118 is positioned above the inlet 104 and theoutlet 106, the pump is started again to initiate the next suction cycle(with a reduced effective volume). The flexible second reservoir 102 inFIGS. 8a, 8b and 8c may be replaced with a rigid second reservoir 102,e.g. the second reservoir 102 according to FIGS. 6a, 6b and 6 c.

FIG. 9a schematically represents an aspiration hose 46 with a valvemechanism 120 in a blocking position, FIG. 9b schematically representsthe aspiration hose 46 in FIG. 9a with the valve mechanism 120 in anopen position and FIG. 9c schematically represents the aspiration hose46 in FIGS. 9a and 9b with the valve mechanism 120 in an intermediateposition. The aspiration hose 46 in FIGS. 9a, 9b and 9c may be used withany canister 42 and medical aspirator 10 according to the presentdisclosure to suction bodily fluids and secretions from a patient intothe canister 42.

The aspiration hose 46 comprises a main channel 122 through which thesuctioned fluids flow. The valve mechanism 120 separates the mainchannel 122 into an upstream section 124 and a downstream section 126.The upstream section 124 is the section adjacent to a suction opening128 of the aspiration hose 46 which is brought into contact with orclose vicinity to a patient area from which fluids are to be suctioned.The downstream section 126 is permanently fixed or detachably attachableto a canister 42, for example to an inlet 104 as shown in FIGS. 5 to 8.

The valve mechanism 120 is in FIG. 9a implemented as comprising a valvemember 130 having an opening part 132 and a closing part 134. In theblocking position of FIG. 9a , the closing part 134 of the valve member130 is aligned with the main channel 122 such that the main channel 122is blocked. Consequently, fluid in the upstream section 124 is preventedfrom entering the downstream section 126.

The valve mechanism 120 comprises a valve mechanism housing 136extending substantially transverse to a longitudinal extension directionof the aspiration hose 46. The valve mechanism housing 136 guides themovement of the valve mechanism 120. More specifically, the valve member130 of the valve mechanism 120 is arranged inside the valve mechanismhousing 136.

A biasing member 138, in FIG. 9a implemented as a compressed spring, maybe mounted inside the valve mechanism housing 136 to exert an upwardforce (in the direction of arrow 140) on the valve member 130 in orderto maintain the valve mechanism 120 in the blocking position. Thus, thevalve mechanism 120 constitutes a normally-closed valve.

The valve mechanism 120 further comprises a stem 142 extending throughan opening in the valve mechanism housing 136 and a button 144 attachedon top of the stem 142. An air inlet 146 constituted by an opening isformed in an upper (as seen in FIG. 9a ) wall of the aspiration hose 46.However, the air inlet 146 may be provided on alternative sides of theaspiration hose 46, e.g. for being obstructed by a finger other than thethumb. When not obstructed, the air inlet 146 establishes a fluidcommunication between the upstream section 124 of the aspiration hose 46and the atmosphere. The air inlet 146 may be intentionally obstructedand cleared by an operator, e.g. with the thumb. For example, the airinlet 146 can be obstructed by the thumb in order to maintain a vacuumwithin the upstream section 124 and the air inlet 146 can be cleared torelease this vacuum if the aspiration hose 46 sticks to patient tissueand the valve mechanism 120 is in the blocking position.

The valve mechanism 120 can be moved from the blocking position in FIG.9a to the open position in FIG. 9b , for example by pushing down thebutton 144, as indicated by the arrow 148. Thus, the valve mechanism 120is switchable between the blocking position and the open position. Bypushing down the button 144, the valve member 130 moves down inside thevalve mechanism housing 136 until the opening part 132 is aligned withthe main channel 122 of the aspiration hose 46. Thereby, the upstreamsection 124 is brought into fluid communication with the downstreamsection 126. In other words, the valve mechanism 120 in the openposition allows fluid to pass from the upstream section 124 to thedownstream section 126 of the aspiration hose 46. A locking mechanism(not shown) may be provided to lock the valve mechanism 120 in the openposition illustrated in FIG. 9 b.

FIG. 9c illustrates the valve mechanism 120 in an intermediate position,between the blocking position in FIG. 9a and the open position in FIG.9b . As can be seen in FIG. 9c , when the valve mechanism 120 adoptsthis intermediate position, the valve member 130 is positioned such thatits opening part 132 is offset with respect to the main channel 122.Thereby, the fluid communication between the upstream section 124 andthe downstream section 126 is partly restricted. With the valvemechanism 120 according to FIGS. 9a, 9b and 9c , the valve member 130 ofthe valve mechanism 120 can accomplish any restriction (from fullrestriction to no restriction) to the main channel 122 by moving thevalve member 130 inside the valve member housing 136. That is, aplurality of intermediate positions can be adopted by the valvemechanism 120.

FIG. 10a schematically represents a further aspiration hose 46 with avalve mechanism 120 in a blocking position and FIG. 10b schematicallyrepresents the aspiration hose 46 in FIG. 10a with the valve mechanism120 in an open position. Mainly differences with respect to FIGS. 9a, 9band 9c will be described.

Instead of the air inlet 146 according to FIGS. 9a, 9b and 9c , thevalve mechanism 120 in FIG. 10a comprises an air inlet channel 150between the upstream section 124 and the atmosphere through the valvemechanism housing 136. In FIG. 10a , the air inlet channel 150 is ledthrough the lower part of the valve mechanism housing 136 where thebiasing member 138 is provided. The air inlet channel 150 ends with anair inlet 146.

In the blocking position of the valve mechanism 120 in FIG. 10a , theclosing part 134 is raised above the air inlet channel 150. Thus, theair inlet channel 150 is only negligibly obstructed by the biasingmember 138. Thus, when the valve mechanism 120 adopts the blockingposition, the upstream section 124 is in communication with theatmosphere, but not with the downstream section 126.

When the valve mechanism 120 is maneuvered from the blocking position inFIG. 10a to the open position in FIG. 10b , the opening part 132 of thevalve member 130 is moved into alignment with the main channel 122 andthe upstream section 124 is consequently brought into fluidcommunication with the downstream section 126. At the same time, theclosing part 134 of the valve member 130 is moved from alignment withthe main channel 122 and into a lower position within the valvemechanism housing 136 where it blocks the air inlet channel 150 suchthat communication between the atmosphere and the upstream section 124is prevented. In other words, the valve mechanism 120 is configured suchthat fluid communication between the upstream section 124 and theatmosphere is closed when the valve mechanism 120 adopts the openposition.

The aspiration hose 46 in FIGS. 9a, 9b, 9c, 10a and 10b may be operatedas follows. With a method for controlling the vacuum generated by avacuum pump 18 driven by a motor 38 in a medical aspirator 10 asdescribed herein, the pump 18 will stop when a desired vacuum set pointis reached. Thus, when the valve mechanism 120 adopts the blockingposition, the level of vacuum inside the downstream section 126 of theaspiration hose 46 will increase until a target vacuum level is reached.

When the target vacuum level is reached, the pump 18 will stop. Thus,the aspiration hose 46 may be brought to the vicinity of a patient withthe valve mechanism 120 in the blocking position and the motor 38 turnedoff.

As the medical suction operation is to be initiated, the operatoractuates the valve mechanism 120, e.g. by pushing the button 144downwardly in the direction 148. As soon as the opening part 132 of thevalve member 130 establishes a fluid communication between the upstreamsection 124 and the downstream section 126, air (and/or fluids) insidethe upstream section 124 will move into the downstream section 126.Since the vacuum level inside the downstream section 126 is therebydecreased, the vacuum pump 18 will be activated to re-establish thetarget vacuum level.

The operator can adjust the airflow through the aspiration hose 46 bymoving the valve mechanism 120 between the blocking position, the openposition and any intermediate position. Thus, the valve mechanism 120 isused as an on/off actuator for the vacuum pump 18. In case theaspiration hose 46 according to FIGS. 9a, 9b and 9c is used, theoperator may simultaneously obstruct the air inlet 146 with the thumb inorder to maintain the vacuum inside the upstream section 124. Thisfunction may however also be controlled with the valve mechanism 120, asexemplified in FIGS. 10a and 10 b.

In case the suction opening 128 sticks to the patient, the operator canremove the thumb from the air inlet 146 in FIGS. 9a, 9b and 9c . In casethe valve mechanism 120 in FIGS. 10a and 10b is used, a deactivation ofthe valve mechanism 120 (e.g. pressure relief on the button 144) bringsthe upstream section 124 in communication with the atmosphere such thatvacuum inside the upstream section 124 is relieved and the suctionopening 128 can easily be removed from a target site of the patient.

While the present disclosure has been described with reference toexemplary embodiments, it will be appreciated that the present inventionis not limited to what has been described above. For example, it will beappreciated that the dimensions of the parts may be varied as needed.Accordingly, it is intended that the present invention may be limitedonly by the scope of the claims appended hereto.

1. Vacuum pump for a medical aspirator, the pump comprising: a tubularmember; a piston slidably arranged within the tubular member; a pistonrod connected to the piston; and a coupling mechanism for detachably andfunctionally connecting the piston rod to a motor for driving the pump.2. The vacuum pump according to claim 1, further comprising a drivemechanism configured to translate a rotary motion of the motor to alinearly reciprocating motion of the piston rod and wherein the couplingmechanism is provided on the drive mechanism.
 3. The vacuum pumpaccording to claim 1, further comprising a membrane fixed to the pistonrod for sealingly closing the pump.
 4. Vacuum pump for a medicalaspirator, the pump comprising: a tubular member; a piston slidablyarranged within the tubular member; a piston rod connected to thepiston; and a membrane fixed to the piston rod for sealingly closing thepump.
 5. Motor unit for a medical aspirator, the motor unit comprising:a motor for driving a vacuum pump; at least two batteries, where eachbattery is configured to supply drive current to the motor; a relayassociated with each battery, wherein each relay is configured tooperate between an allowing state for receiving a charge from a mainspower supply, and a non-allowing state in which the charge from themains power supply is not allowed.
 6. The motor unit according to claim5, wherein the relays of the batteries are galvanically separated fromeach other.
 7. The motor unit according to claim 5, further comprising acontrol unit configured to control the at least two batteries toalternatingly supply drive current to the motor.
 8. The motor unitaccording to claim 7, wherein the control unit is configured toalternatingly control the relays such that the relay of the battery thatcurrently supplies drive current to the motor adopts the non-allowingstate and the relay of each one or more remaining batteries adopt theallowing state so that the motor is never electrically connected to themains power supply.
 9. Medical aspirator comprising a vacuum pumpaccording to claim
 1. 10. Disposable arrangement comprising: a firstdisposable part connectable to a second part, or forming a jointstructure together with the second part; a flexible enclosure configuredto provide a protective shield around the second part during use of thefirst disposable part together with the second part, and configured tobe inverted to provide a protective shield around the first disposablepart after completion of the use.
 11. The disposable arrangementaccording to claim 10, wherein the flexible enclosure is a plastic bag.12. The disposable arrangement according to claim 10, wherein theflexible enclosure comprises a closable opening which in an opencondition allows the flexible enclosure to be inverted from a stateenclosing the second part to a state enclosing the first disposable partand which in a closed condition forms a part of a substantially fluidtight seal around the second part and the first disposable part,respectively.
 13. The disposable arrangement according to claim 12,wherein the closable opening is constituted by a zip-lock.
 14. Thedisposable arrangement according to claim 10, wherein: the firstdisposable part is constituted by a pump unit with a vacuum pump; for amedical aspirator; the second part is constituted by a motor unit with amotor for the medical aspirator, where the vacuum pump is drivable bythe motor; and the flexible enclosure is configured to provide abacterial shield around the motor unit during a suction operation of themedical aspirator, and configured to be inverted to provide a bacterialshield around the pump unit after completion of the suction operation ofthe medical aspirator.
 15. The disposable arrangement according to claim14, wherein the vacuum pump comprises a membrane and the flexibleenclosure is integrally formed with the membrane.
 16. Medical aspiratorcomprising: a disposable arrangement according to claim 14; and a motorunit comprising a motor for driving the vacuum pump of the pump unit.17. The medical aspirator according to claim 16, wherein the pump unitis detachably connectable to the motor unit.
 18. An arrangement forinactivating infectious agents in an air stream, such as an air streamwithin a medical aspirator, the arrangement comprising: a channel forguiding an air stream therethrough, the channel being at least partlyconstituted by a material permeable to ultraviolet light; and anultraviolet light source arranged adjacent to the channel configured toexpose the air stream within a treating section of the channel toultraviolet light.
 19. The arrangement according to claim 18, whereinthe channel within the treating section comprises at least two channelsegments configured to direct the air stream in different directions.20. The arrangement according to claim 18, wherein the channel withinthe treating section is arranged as a spiral, coil or helix and/orcomprises a plurality of substantially parallel channel segments. 21.Medical aspirator comprising an arrangement according to claim
 18. 22.(canceled)
 23. (canceled)
 24. Two-stage canister, the canistercomprising: a first reservoir for an aspiration hose and an outlet for avacuum channel; a second reservoir; and a partition member movable froma closed position, where the partition member is configured to maintaina fluid within the first reservoir and where an effective volume forvacuum buildup in the canister is reduced, to a drain position in orderto drain the fluid within the first reservoir to the second reservoir.25. The two-stage canister according to claim 24, wherein both the firstreservoir and the second reservoir are configured to withstand a reducedpressure during operation of the two-stage canister with the partitionmember in the drain position.
 26. The two-stage canister according toclaim 24, wherein the second reservoir is flexible.
 27. The two-stagecanister according to claim 24, wherein the partition member is movablefrom the drain position to the closed position.
 28. The two-stagecanister according to claim 24, wherein the partition member comprises aclosing piston for sealingly closing the first reservoir to the secondreservoir when the partition member is in the closed position.
 29. Thetwo-stage canister according to claim 28, wherein the partition membercomprises a piston rod attached to the closing piston and the piston rodextends through the exterior of the first reservoir.
 30. The two-stagecanister according to claim 28, wherein the partition member comprises apressing piston for pressing the fluid within the first reservoir to thesecond reservoir during movement of the partition member from the closedposition to the drain position.
 31. Medical aspirator comprising atwo-stage canister according to claim
 24. 32. Medical aspiratorcomprising: a vacuum pump; a motor configured to drive the vacuum pump;a control unit; and an aspiration hose for suctioning fluids from apatient into a canister of the medical aspirator; wherein the aspirationhose comprises: an upstream section; a downstream section; and a valvemechanism switchable between an open position and a blocking position,wherein the valve mechanism is configured to allow the suctioned fluidsto pass from the upstream section to the downstream section in the openposition, and to block the suctioned fluids in the upstream section fromentering the downstream section in the blocking position.
 33. Themedical aspirator according to claim 32, wherein the aspiration hosefurther comprises a biasing member configured to bias the valvemechanism into the blocking position.
 34. The medical aspiratoraccording to claim 32, wherein the aspiration hose further comprises anair inlet for fluid communication between the upstream section and theatmosphere when the valve mechanism adopts the blocking position. 35.The medical aspirator according to claim 34, wherein the aspiration hoseis configured such that fluid communication between the upstream sectionand the atmosphere is closed when the valve mechanism adopts the openposition.
 36. The medical aspirator according to claim 31, furthercomprising a canister comprising an aspiration hose according to claim32.
 37. (canceled)
 38. The medical aspirator according to claim 32,wherein the control unit is configured to control a drive currentsupplied to the motor based on a vacuum generated by the vacuum pump.39. The vacuum pump according to claim 1, wherein the piston rod isconfigured to reciprocate linearly during operation of the pump.
 40. Thevacuum pump according to claim 4, wherein the piston rod is configuredto reciprocate linearly during operation of the pump.
 41. Medicalaspirator comprising a vacuum pump according to claim
 4. 42. Medicalaspirator comprising a motor unit according to claim 5.